What we’re learning about dairy mobbing

By Cheyenne Christianson

Chetek, Wisconsin—As most of you know from my previous articles, over the past two years I have taken steps toward “mob” grazing — especially with the non-milking cattle. We went through a multi-year drought and, as I analyzed my farm, its growth patterns and fertility levels, I realized we needed to take some steps to offset the next drought. With our sandy loam topsoils and pure sand subsoils, we were drying out too fast.

I felt we needed to do something to capture more of those big dumps that seemed to be the source of most of the rain we did get — things like trampling more organic material to provide a soil mat that would retain more moisture, and feeding the soil life that builds humus and organic matter, became top priorities. I am intrigued by the concept of soil biology releasing tied-up nutrients in the soil. Over the years I have applied some trace minerals, rock phosphate and high-calcium lime, and have done some foliar feeding. However, a truly sustainable/organic farming system should be pretty much self-sufficient, and it appears that mobbing may make that goal more possible.

We run four groups of cattle here: the milking herd, the nurse-cow group that raises the calves, a “heifer” group that can include everything from yearlings on up to a few dry cows, and a bull herd of yearlings and a few two-year olds. All four groups are moved to new pasture twice a day, with the milking herd moved a third time at mid-afternoon on many days.

For me, mob grazing involves trampling a tall, mature stand to the ground so that regrowth starts from the ground. Back-fencing is moved every one to three days, with sooner being better so regrowth can start right away. However, sometimes an extra day helps trample the wastage better. I figure about 140,000 lbs. of liveweight per acre for each grazing break. We do move the heifers in the middle of the day at times, so that would push up the weight per acre a fair bit.

The goal is to move herds through the paddocks three or four times during the course of the season. The mobbed fields can still get two additional passes, although last year a dry fall kept us to two rotations on those fields, with a short third pass.

We are not doing this kind of grazing with the milking herd, and we really haven’t changed the milk cow grazing all that much from what we’d been doing over the previous 10 years or so. They always ran through some fairly mature pasture at times, but only for short durations while alternating with higher-quality forage. I never pushed them on the very tall forage, so it was not trampled. We clipped the refusal.

Now, if the cows leave some extra, I let it regrow and run the heifer or bull group in the next rotation to trample what the cows left behind. I’d estimate milking cows are stocked at 75,000 to 90,000 pounds per acre depending on the field, forage quality, and how much of the plant I want them to eat. But we also give the extra break in the afternoon at times, so that increases the stocking.

It’s not uncommon for my milking cow pastures to have headed-out grasses and legumes in bloom, but the plants are on the immature, green side. White clover in these stands provides a little more protein.

The nurse cow group had 14 to 17 cows and at least 30 calves, and was grazed at the same stocking rate as the milking herd on three- to four-foot tall forage, although last year the forage wasn’t fully mature. The calves did great.

However, we may have had some less than ideal results from grazing the milking herds on pastures that were too mature. We had periods of heavy rainfall in 2011, although we did have a dry spell at mid-summer. That made me nervous about another drought, so instead of skipping some of the more mature pasture like I normally would, I kept that pasture in the rotation, which was the second of the season. The clovers were getting mature and the grass was losing its lush, green look, although it was not as rank as the first growth would have been.

I felt the cows could have been milking better and gaining more weight. We tend to peak at close to 50 lbs./cow in spring/early summer before dropping back to around 40 lbs. by mid-summer.

Overall, the milking cattle weren’t thin this past year, but they just maintained the same condition all summer. It wasn’t until we started grazing the fall oats that the cows really gained condition and got their nice, oily coats. We had some warmer weather, which may have caused the plants to lignify, possibly creating another issue.

Next year we’ll graze the cows on some greener pastures to see if that makes a difference. We’ll still turn in to forages that are knee-high or taller, but they won’t all be quite as ripe. We should be able to maintain a higher level of milk production for a longer period if I keep working on it while improving the nutrient density of my forages. Then again, I do like experimenting, and this does cost me some production. I can deal with lost milk, but crashing the body condition, breeding or long-term health of my cows can have lasting implications. I’ll keep experimenting with maturities to see what’s possible on this farm, but I caution anyone wanting to mob graze milking animals on mature forage to go slow.

We had another great year of mob grazing the heifer and bull groups. I noticed that you really have to watch your animals when everything goes ripe and before new growth fills in. For me, that period is mid- or late-June through July. We were giving the heifers and bulls the same size of break all along until I noticed the heifers losing their shiny hair coat. I had been making them eat at least three-fourths of the forage, when maybe half to two-thirds would have been better. So we started giving them a little more grass. We wasted a little more, but I don’t think we’d been leaving enough litter in the first place.

I really think that we dairy farmers can do the same things with our non-milking animals that beef farmers are doing with their cattle. I’m seeing weight gains and frame growth just as good as I’ve ever had on this farm. For the young stock, we’ll keep doing what we’ve been doing.

I do like what mob grazing appears to be doing for my pastures. After the cattle move through, the grass dies and looks brown for a few days, and at times it looks like the new grass will be smothered out. But after a couple of days, the new leaves are coming through, and after two weeks the stand is thickening up well. In mature pasture the seeds start to germinate and grow — the number of new seedlings is incredible. This regrowth is like hair, and it is actually much thicker than the original stand — contrary to some claims that a stand will thin as time goes on with mob or “tall” grazing.

During our dry spell, it was interesting to see the ground still moist under the ungrazed, mature portion of the pastures when everything else was dry at the surface. We also got 10 inches of rain in two weeks during late July, with the last seven of those inches coming in two- to three-inch pours over a three-day period. The waste from the mobbing formed a mat that protected the ground: They barely made any tracks, even though the ground felt like mush under my feet! We did keep them moving to avoid the chance that they would track it up.

I am almost certainly giving up some yield compared to if I was running four grazing rotations during the season. I have to do some more comparison in this area, although right now I’m fine with giving up some yield in order to build soil.

There is also the issue of needing organic bedding — the mature forage would be a good source of that. But we have taken a lot of hay off certain fields in recent years, so I wanted to leave the residue to see what it will do for the soils and the pastures. I think this will provide future benefits in terms of better yields and soil tilth.

It seems that weather patterns are changing, and it will take some adapting to make the best of the situation. I’m excited about figuring out ways to capture the rain that falls on my farm, and continuing to build organic matter and soil life to survive the next drought.

Cheyenne Christianson milks cows near Chetek, Wisconsin.